Device for feeding pressurized liquid to a hydraulic circuit

ABSTRACT

A device is provided for feeding pressurized liquid to a hydraulic circuit of a hydraulic actuation element. The device includes a motor, a flywheel and a positive displacement pump. The positive displacement pump and the flywheel are mounted on a common shaft. The device also includes a flywheel containment structure suitable for retaining the flywheel in the event of accidental breakage, and a motion transmission element. The containment structure rigidly supports a pair of seats for shaft bearings, and a seat for the pump.

This application is a 371 of PCT/EP92/01224, Jun. 02, 1992.

This application is a 371 of PCT/EP92/01224, Jun. 02, 1992.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for feeding pressurized liquidto a hydraulic circuit of a machine which comprises a hydraulicactuation element. For the description of a machine which comprises ahydraulic actuation element and a hydraulic circuit suitable for beingfed by the device according to the invention, reference is made to thehydraulic press described in the PCT patent application no. PCT/EP89/00610. The term "liquid" is used herein to generally refer tohydraulic oil, emulsions thereof, or to other liquids suitable for beingused in hydraulic circuits for the actuation of hydraulic actuationelements.

The field of the present invention relates to devices which comprise amotor, a flywheel mounted on a shaft, a positive-displacement pumpmounted on said shaft, a flywheel containment and supporting structure,and a motion transmission element suitable for transmitting the motionfrom said motor to said shaft.

The positive-displacement pump generally operates at rather highpressures, in excess of 100 bar, often higher than 200 bar, with peaksof over 300 bar. The momentary power transmitted from the flywheel tothe pump is very high, up to 300-400 kw.

The above is in summary the main field of industrial use of theinvention, but does not constitute a limitation of the scope thereof,since the device according to the invention, in particular ashereinafter described and claimed, can be advantageously used in anyother equivalent field in which it is necessary to feed pressurizedliquid, at a variable pressure during the working cycle, and inparticular when it is necessary to transmit an extremely high momentarypower.

2. Description of the Prior Art

Devices of this type are known and are described for example in the PCTpatent no. PCT/EP 89/00610 in the name of the same Applicant, whereinthe shaft on which the Dump and the flywheel are mounted is the motorshaft and said shaft is supported by the internal bearings of the motor.

Said known devices, however, entail some problems, since it is obviouslyimpossible to mount more than one pump for each flywheel, and thecontainment of all the kinetic energy stored in the flywheel isentrusted exclusively to the bearings of the motor, which have not beendesigned for this purpose. It is furthermore difficult to try to mountfurther additional bearings, due to problems of coaxiality with themotor shaft. In view of the fact that the flywheel rotates atapproximately 1800 rpm for these applications, it can be easilypredicted that safety problems arise, especially in cases in which largeflywheels are required. A vault-shaped structure, arranged over theflywheel, in order to protect the surrounding area, is in fact generallyprovided due to safety problems.

Japanese patent applications JP-A-56-111593 and JP-A-56-111594 describea supporting structure of a flywheel connected with a pump group by anelectromagnetic clutch.

This arrangement gives rise to some problems: an electromagnetic clutchcan only transmit a limited power and is a complex device which caneasily break under heavy loads; furthermore some of the energy generatedby the flywheel is lost and is converted into heat for the frictioninside the clutch. It is impossible to use standard pumps, since thedescribed twin pumps require a special manufacture. The centering of theseats of the pump and of the bearings of the flywheel is complex andrequires a long and expensive working process.

U.S. Pat. No. 3,756,751 describes a clutch housing in which a hydraulicpump is connected with a flywheel by gears. This solution cannot ofcourse transmit high momentary power, since only the power sustained bythe gears can be transmitted.

Canadian patent No 1144784 describes some housings for flywheels, butdoes not disclose anything about the connection with a pump.

SUMMARY OF THE INVENTION

The aim of the present invention is therefore to overcome the abovedisadvantages by providing a very compact device which can transmitsafely very high momentary power.

Another aim of the invention is to be able to determine the motiontransmission ratio between the motor and the shaft, so as to be able tomaximally exploit the characteristics of the pump and of the flywheel.

Another aim of the invention is to be able to mount larger and fasterflywheels while providing the fullest safety for the surrounding areaand people.

Another aim of the invention is to ensure complete modularity inindustrial production, so that in order to replace the pump with anotherone, even with a different model, it is sufficient to change thesupporting flange of the pump. The same device is therefore suitable fora plurality of machines of different sizes, for each of which it issufficient to adopt a specific type of pump and a specific flywheelthickness, without having to provide different devices for each type ofmachine.

Another aim of the invention is to be able to mount two standard pumpscoupled to the same flywheel and also to allow said two pumps to be veryclose to one another and thus be easy to hydraulically couple. It is infact very important for the pumps to be close to one another, due to theproblems related to the compressibility of hydraulic oil and to theexpandability of the connecting pipes. In order to achieve high speeds,the volume of the oil to be compressed and the volume generated by theexpansion of the pipes must in fact be minimal. This can be achievedonly if the pumps are very close to one another and therefore the lengthof the connecting pipes is minimal. This object is particularlydifficult to achieve with standard pumps, since through-shaft pumps,which allow a close connection of the pumps themselves, are not usuallyavailable for the high pressures at which the devices according to thefield of the present invention operate.

Another aim of the invention is that of providing a device which isvirtually maintenance free.

And a further object of the invention is to provide a control unit whichhas very small overall dimensions and a modest overall cost.

This aim, these objects and others are achieved according to a firstaspect of the invention by a device for feeding pressurized liquid to ahydraulic circuit, said device being of the type having: a motor, aflywheel mounted on a flywheel shaft, a positive-displacement pumphaving a pump shaft mounted on said flywheel shaft with a coupling whichprevents any possible rotation between said flywheel shaft and said pumpshaft, a containment and supporting structure for said flywheel and amotion transmission element suitable for transmitting the motion fromsaid motor to said flywheel: shaft: an axis of said flywheel shaft andan axis of said pump shaft being exactly the same; said structurerigidly supporting: a first seat for supporting a first bearing of saidflywheel shaft, a second seat for supporting said pump.

A second aspect of the invention provides a device for feedingpressurized liquid to a hydraulic circuit, said device being of the typehaving: a motor, a flywheel mounted on a flywheel shaft, apositive-displacement pump having a pump shaft mounted on said flywheelshaft, a containment and supporting structure for said flywheel and amotion transmission element suitable for transmitting the motion fromsaid motor to said flywheel shaft; an axis of said flywheel shaft and anaxis of said pump shaft being the same; said structure rigidlysupporting:

a) a first seat for supporting a first bearing of said flywheel shaft,and

b) a supporting member which supports both a pump seat for supportingsaid pump and a third seat for supporting a second bearing of saidflywheel shaft.

A third aspect of the invention provides a device for feedingpressurized liquid to a hydraulic circuit, said device being of the typehaving: a motor, a flywheel mounted on a flywheel shaft, apositive-displacement pump having a pump shaft mounted on said flywheelshaft, a containment and supporting structure for said flywheel and amotion transmission element suitable for transmitting the motion fromsaid motor to said flywheel shaft; an axis of said flywheel shaft and anaxis of said pump shaft being the same: said structure rigidlysupporting: a first seat for supporting a first bearing of said flywheelshaft, a second seat for supporting said pump, a third seat forsupporting a second bearing of said flywheel shaft, and lifting meansfor lifting said flywheel with respect to a position identified by saidbearings.

A fourth aspect of the invention provides a process for manufacturing adevice for feeding pressurized liquid to a hydraulic circuit, saiddevice being of the type having: a motor, a flywheel mounted on a shaft,a positive-displacement pump mounted concentrically on said shaft, acontainment and supporting structure for said flywheel and a motiontransmission element suitable for transmitting the motion from saidmotor to said shaft: said structure rigidly supporting: a first seat forsupporting a first bearing of said shaft, a second seat for supportingsaid pump: said process comprising a step in which during the working ofsa;,l first seat and of said second seat on a machine tool, saidstructure is maintained in the same working position on saidmachine-tool.

Said containment structure preferably rigidly supports a fourth seat forsupporting a second pump mounted on another end of-said flywheel shaft.In this manner it is possible to easily couple two standard pumps to thesame flywheel.

The flywheel preferably has a diameter comprised between 30 and 100 cmand more preferably comprised between 50 and 76 cm.

The invention furthermore relates to a machine and in particular to ahydraulic press which comprises a hydraulic actuation element and ahydraulic circuit fed by a device according to the invention. Forwhatever is required for the description of a hydraulic press suitablefor being fed by the device according to the invention, reference ismade the description of the hydraulic press provided in the patentapplication PCT/EP 89/00610.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will becomeapparent from the description of two preferred but not exclusiveembodiments of the device, illustrated only by way of non-limitativeexample in the accompanying drawings, wherein:

FIG. 1 is a partially sectional side view of a first embodiment of thedevice according to the invention;

FIG. 2 is a side view of the device according to the invention, taken onthe side opposite to the one of FIG. 1;

FIG. 3 is a partially sectional front view of the first embodiment ofthe device according to the invention;

FIG. 4 is a partially sectional side view of a second embodiment of thedevice according to the invention;

FIG. 5 is a partially sectional front view of the second embodiment ofthe device according to the invention;

FIG. 6 is a perspective exploded view of the coupling between pump shaftand flywheel shaft.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 to 6, the positive-displacement pump 10 ismounted on a shaft 11, on which a flywheel 12 is also mounted. Acontainment and supporting structure 8 of the flywheel 12 has athickness which is sufficient to retain said flywheel 12 in case of anyaccidental breakage, since it contains said flywheel completely. A motor19 transmits its own motion to the shaft 11 by means of a motiontransmission element 16, 17 and 18. Said motion transmission element hasa presettable transmission ratio, and is constituted in particular bythe first pulley 17, which is keyed on the flywheel shaft 11, and by thesecond pulley 16, which is keyed on the motor 19. The pulleys 16 and 17are connected by means of the belts 18. The transmission ratio betweenthe motor 19 and the shaft 11 can be preset by means of the diameter ofthe pulleys 16 and 17: by changing the relative diameter of said pulleysit is possible to vary the transmission ratio. The first pulley 17 isarranged between the flywheel 12 and the pump 10. Particularly,according to FIG. 1, the first pulley 17 is arranged between a secondbearing 23 and the pump 10.

The containment and supporting structure 8 rigidly supports a first seat9 for supporting a first bearing 22 of the flywheel, a second seat 20for supporting the second bearing 22 of the flywheel shaft 11. Thesecond seat 20 supports also the pump 10. Particularly there is provideda supporting member 15 which is arranged on the second seat 20 and whichsupports a third seat 7 for tile second bearing 23 and a pump seat 25.

The containment structure 8 rigidly supports a fourth seat 21 for asecond positive-displacement pump 26 which is mounted on the other endof the flywheel shaft 11.

With particular reference to FIG. 6, the pump 10 has a pump shaft 6which is mounted on the flywheel shaft 11 with a coupling which preventsany possible rotation between the flywheel shaft 11 and the pump shaft6. This is achieved by a connecting body 5 which is arranged and splinedinside the flywheel shaft 11 and outside said pump shaft 6. Particularlythe connecting body 5 comprises outer connecting means 4 and innerconnecting means 3 which comprise splines for engaging respectivelycomplementary splines provided inside said flywheel shaft 11 and a keyprovided on the pump shaft 6. According to this solution, the connectingbody 5 allows a full modularity, because the same flywheel shaft can beused and it can be adapted to each pump shaft by simply changing theconnecting body 5.

With particular reference to FIGS. 1-3 and to the first embodiment ofthe invention, the pump 10 is supported in seat 25 by means of a flange27. The second pump 26 is mounted on the other end of the flywheelshaft. 11 and particularly on the flange 24.

The motor 19 is preferably supported by the containment structure 13, 14and 15, and in its preferred embodiment is arranged directly above thecontainment structure.

The structure 8 has the shape of a hollow cylinder 13 provided with twocovers 14 and 15; the first cover 14 supports the first seat 9 of thefirst bearing 22 of the shaft 11 and the fourth seat 21 for the pump 26,by means of the flange 24. The second cover 15 is arranged on the secondseat 20 and supports the second bearing 23 and the pump seat 25 for thepump 10.

With a particularly compact solution, the second cover 15 supports aseat 29 for containing the motion transmission element 16, 17 and 18,and in particular the pulley 17, so as to allow the exit of the belts 18through the opening 30. The pump seat 21 for the pump 26 is defined onsaid cover 14.

Preferably, for a greater stability of the entire structure, and for aneven more compact execution, the containment structure 8 is supported ona base 31 and protrudes below said base with the part 32.

With particular reference to FIG. 2 and 5; a general view of the devicemounted on the base 31 is shown. The heat exchanger 33, the accumulator34 and the oleodynamic block 35 are mounted on the same base 31 forgreater compactness. For the operation of said elements 33, 34 and 35,reference is made to application no. PCT/EP 89/00610.

With particular reference to FIG. 3, it is shown the part 32 of thecontainment structure protruding below the base 31 so as to be arrangedin an adapted pit formed in the floor 36. In the upper part, thecontainment structure 13, 14 and 15 is supported by a system of ridges37 which also support the motor 19. In particular the flange 24, onwhich the pump has not been mounted yet, is visible.

With particular reference to FIGS. 4-6, and to the second preferredembodiment of the invention, the containment and supporting structure 8comprises a base 31 which is rigidly connected with uprights 40. A partof the flywheel 12 is arranged inside the base 31. Lifting means 41 areprovided for lifting the flywheel 12 with respect to the positionidentified by the bearings 22 and 23. Particularly, the lifting means 41comprise tie members 42 which lift the flywheel tightening the bolts 43,if bolts 45 are removed. The lifting means 41 allow an easy assembly anddisassembly of the flywheel, of the pumps and of the bearings.

A supporting member 44 is arranged on the first seat 9 so that it canslide on it except when the bolts 45 are tightened. The supportingmember 44 supports the first bearing 22 and the fourth seat 21 for thepump 26.

A supporting member 15 is arranged on the second seat 20 so that it canslide on it except when the bolts 45 are tightened. The supportingmember 15 supports the third seat 7 for the second bearing 23 and thepump seat 25 for the pump 10.

The sliding of the supporting members 15 and 44 allow an easy assemblyand disassembly of the flywheel, of the pumps and of the bearings,maintaining a perfect centering during the sliding.

The first pulley 17 is arranged between the flywheel 12 and a secondbearing 23 of the flywheel shaft 11.

Both the first and the second embodiment of the invention can bemanufactured according to the claimed process, and particularly, duringthe working of the first seat 9 and of the second seat 20 thecontainment and supporting structure 8 is maintained in the same workingposition on a machine-tool. so as to ensure a perfect centering andlinearity of the seats and allow full coaxiality between the pumps andthe flywheel.

The invention is susceptible to numerous modifications and variations,all of which are within the scope of the same inventive concept; inparticular, the motion transmission element can be for example replacedwith a pair of gears, coupled directly or by means of a chain, with aresult which is less convenient but sufficient for several uses.Similarly, the various elements may be replaced with other mechanicallyequivalent ones.

What is claimed is:
 1. A device for feeding pressurized liquid to ahydraulic circuit, said device comprising: a motor, a flywheel mountedon a flywheel shaft, a positive-displacement pump having a pump shaftmounted on said flywheel shaft with a coupling which prevents anypossible rotation between said flywheel shaft and said pump shaft, acontainment and supporting structure for said flywheel and a motiontransmission element suitable for transmitting motion from said motor tosaid flywheel shaft; an axis of said flywheel shaft and an axis of saidpump shaft being exactly the same; said structure rigidly supporting: afirst seat for supporting a first bearing of said flywheel shaft, asecond seat for supporting said pump, and a supporting member whichsupports both a pump seat for supporting said pump and a third seat forsupporting a second bearing of said flywheel shaft.
 2. The deviceaccording to claim 1 in which said structure rigidly supports liftingmeans for lifting said flywheel with respect to a position identified bysaid bearings.
 3. The device according to claim 1 in which saidstructure rigidly supports a fourth seat for supporting a second pumpmounted on another end of said flywheel shaft.
 4. The device accordingto claim 1, in which said motion transmission element comprises a belt,a first pulley keyed on said flywheel shaft, and a second pulley keyedon said motor; said first pulley being arranged between said flywheeland said pump.
 5. The device according to claim 4 in which said firstpulley is arranged between said flywheel and said second bearing of saidflywheel shaft.
 6. The device according to claim 4, in which said firstpulley is arranged between said second bearing of said flywheel shaftand said pump.
 7. The device according to claim 1, in which said firstseat supports said first bearing by a supporting member which can slideon said first seat, except when the supporting member is tightened. 8.The device according to claim 1, in which said second seat supports saidpump by a supporting member which can slide on said second seat, exceptwhen the supporting member is tightened.
 9. The device according toclaim 1, in which said structure has the shape of a hollow cylinderprovided with two covers, a first cover for supporting said first seat,and a second cover for supporting said pump, said structure rigidlysupporting a fourth seat for supporting a second pump mounted on anotherend of said flywheel shaft.
 10. The device according to claim 9,characterized in that said first cover supports said fourth seat. 11.The device according to claim 9, characterized in that one of saidcovers supports a seat for said motion transmission element.
 12. Thedevice according to claim 1 in which said structure has a base, andwherein a part of said flywheel is arranged inside said base.
 13. Thedevice according to claim 1, in which said flywheel has a diameterbetween approximately 30 cm and 100 cm.
 14. The device according toclaim 1 in which said flywheel has a diameter between approximately 50cm and 76 cm.
 15. A device for feeding pressurized liquid to a hydrauliccircuit, said device comprising:a motor; a flywheel mounted on aflywheel shaft; a positive displacement pump having a pump shaft; amotion transmission element to transmit motion from said motor to saidflywheel shaft;. a support structure for said flywheel, said supportstructure rigidly supporting a first seat which supports a first bearingof said flywheel shaft, and a second seat which supports said pump; anda connecting body coupling said pump shaft to said flywheel shaft alongan identical axis, said connecting body preventing any possible rotationbetween said flywheel shaft and said pump shaft, said connecting bodyincluding outer connecting means for engaging an inner portion of saidflywheel shaft, and inner connecting means for engaging an outer portionof said pump shaft.
 16. The device according to claim 15 in which saidouter connecting means includes a plurality of splines, and saidflywheel shaft includes a plurality of correspending splines to engagesaid plurality of splines.
 17. The device according to claim 15 in whichsaid inner connecting means includes a splines, and said pump shaftincludes a key to engage said spline.
 18. An apparatus comprising:ahydraulic actuation element; a hydraulic circuit; and a device forfeeding pressurized liquid to said hydraulic circuit to actuate saidhydraulic actuation element, said device including: a motor; a flywheelmounted on a flywheel shaft; a positive displacement pump having a pumpshaft coupled to said flywheel shaft along an identical axis; a motiontransmission element to transmit motion from said motor to said flywheelshaft; and a containment and supporting structure for said flywheel,said structure rigidly supporting a first seat which supports a firstbearing of said flywheel, a second seat for supporting said pump, and asupporting member which support both a pump seat for supporting saidpump and a third seat for supporting a second bearing of said flywheelshaft.